CCL2 and infection: To investigate the role of inflammatory response in the intestinal tissue in decreasing C. difficile numbers, we performed RTq-PCR to measure the mRNA expression of related inflammatory cytokines, i.e., IL-1β, IL-12, Ccl2, CSF, Cxcl1, Reg3-β, Reg3-γ, and TNFα and intestinal mucous proteins Muc2 and Muc3 at day 10 post-infection.